1. Field of the Invention
This invention relates in general to a container valve with pressure reducing function, and more specifically relates to a valve with a structure suitable for a gas container filled with various gases that have the characteristics of being inflammable, spontaneous-flammable, and toxic, corrosive and combustible-supportability.
2. Description of Related Art
Gas used in industry (industrial gas) is often high-pressure gas having dangerous characteristics such as being inflammable, spontaneous-flammable, and toxic, corrosive and combustible-supportability. The gas is supplied to and consumed by consumption equipment. This makes it difficult to maintain safety. Especially in the semiconductor industry, the larger the diameter of a wafer is, the more semiconductor gas with dangerous characteristics consumed. Still severer management must be increasingly performed to maintain safety.
Generally, the method for supplying industrial gas is as follows. The gas is filled into a high-pressure container under high pressure. A pressure regulator is arranged on the gas supplying line. The gas with high-pressure is reduced to a specific consumption pressure (1 Mpa or less is usual) by the pressure regulator. In the High-Pressure Gas Safety Law in Japan, the necessary techniques for using special high-pressure semiconductor gas such as silane, disilane, arsine, phosphine, diborane, hydrogen selenide and germane are stipulated in detail. Even though the consumption thereof is little, the consumption must be registered to the prefectural governor. Especially, parts in the high-pressure portion inside the cylinder cabinet must use the parts authorized by the High-Pressure Gas Safety Institute of Japan, wherein the high-pressure portion is from the connection portion of the container to the pressure regulator. There are two drawbacks: high danger with gas leakage due to the existence of the high-pressure portion and high cost due to using the authorized parts.
On the other hand, sometimes an adsorbent like zeolite or active carbon is filled into the container. The adsorbent absorbs the liquefied gas under pressure lower than the atmospheric pressure, wherein the liquefied gas is like phosphine, arsine, diborane and germane etc. The technique for supplying gas under this condition is practiced where the filling amount is seven to forty times compared with a container with the same volume for filling high-pressure gas without absorbent. Although the technique has great merit in terms of filling amount, it also has the problem that the gas cannot be supplied unless the pressure of consumption equipment is 10 or less than 10 Torr. This technique can only be used in the semiconductor industry using ion implantation or high-density plasma CVD etc. Furthermore, because the absorbent is used, it is difficult to remove the atmospheric impurity absorbed by the adsorbent. Additionally, because the adsorbent is also the source for generating particles, high purity gas cannot be provided.
A container which can supply gas under low-pressure is proposed referring to the Japan Laid-open publication no. 2001-510546, wherein a highly integrally formed pressure regulator and container valve are attached to the container. Since this container is not functional to efficiently fill the container with gas, because it is difficult to exhaust the container into a vacuum state before filling the gas and the filling speed is slow. As a result, the filled gas is of low purity. Furthermore, the remaining amount of gas cannot be managed with the low-pressure inside the container.